When one examines the background art from the standpoint of oil thickening or gelation, the oil-based systems used as cosmetic materials are found to frequently contain a silicone oil, and a problem in such cases has been the poor effects exercised by organic thickeners or gellants. The oil thickening/gelling art is an art that can provide the cosmetic producer with the freedom to freely control the form of a cosmetic formulation, for example, from a liquid form to a cream, paste, gel, or solid, and thus is an extremely important art. As a consequence, much effort has been directed to the development of modified silicone-based thickeners or gellants that are also advantageous with regard to tactile feel and to the application of these modified silicone-based thickeners or gellants to cosmetic materials.
The art of solidifying an oil using an alkyl-modified silicone wax has long been known, but the problems generally associated with this have been, inter alia, a substantial oily feel, a heavy spreadability and tactile feel, a somewhat reduced freedom to control the form and viscosity of the cosmetic material, and a propensity for solidification to occur regardless of the quantity of addition.
Art has also been developed with regard to gel-form silicone compositions, in which a silicone oil is gelled by using a polyether-modified silicone and water (Patent Document 7); however, a problem with this art has been its inadequate thickening•gelling effect when the oil system contains an organic oil. Another problem with respect to the tactile feel has been a slimy and uncomfortable sensation.
On the other hand, the art of oil gelation by, for example, an amino acid derivative-modified silicone or a straight-chain polyamide-modified silicone, and its application to cosmetic materials have also been reported (Patent Documents 8 to 11). While these gellants are excellent in terms of tactile feel, solidification is prone to occur regardless of the quantity of addition, which makes it difficult to freely control the form and viscosity of the cosmetic material. Moreover, due to an excessive solidification and hardening, once the gel surface has been scratched or damaged, recovery to a smooth surface cannot occur and the damage remains intact, which has the disadvantage of an impaired appearance.
Thus, the silicone-type oil gellants provided by the existing art are almost all of a type that ends up causing solidification of the oil, and an excellent oil thickener that makes possible free ranging control of, e.g., the form and viscosity of an oil or cosmetic material based on the quantity of thickener addition is unknown. Also unknown are a material and art that can stably thicken a wide variety of oil systems comprising a silicone oil+organic oil combination.
When one considers the existing art from the perspective of the involvement of (poly)glycerol-modified silicones with the oil thickening•gelation art, the following, for example, have been proposed: cosmetic materials comprising the combination of an organomodified-clay mineral or fructooligosaccharide fatty acid ester known as an oil thickener•gellant, with a silicone- and branched polyhydric alcohol-modified silicone, for example, an alkyl/branched linear siloxane/polyglycerol-co-modified silicone (Patent Documents 12 and 13) and a make-up cosmetic material that contains, in specific proportions, a silicic anhydride known as an oil thickener•gellant and an alkyl glyceryl ether-modified silicone with a specific structure (Patent Document 14).
The (poly)glycerol-modified silicones used in this art in all instances have a low molecular weight and, due to their poor oil thickening•gelation capacity, have had to be used in combination with a separate material that can effectively thicken•gel an oil and have also had an unsatisfactory effect with regard to controlling a cosmetic material to a required viscosity and state. In addition, in some cases the organomodified-clay mineral or silicic anhydride undergoes aggregation due to the influence of the oil species or water fraction and the proposed cosmetic materials have thus had stability problems. The fructooligosaccharide fatty acid esters have an unsatisfactory capacity to thicken•gel silicone oils other than cyclic siloxanes and thus have provided little flexibility with regard to cosmetic material formulation.
A novel organopolysiloxane-glycerol derivative alternating copolymer has quite recently been proposed in Patent Document 15; here, a high molecular weight polyglycerol-modified silicone is obtained free of the problem of the turbidity induced by unreacted starting material. However, as may be understood from its chemical structure, this compound incorporates a hydrophilic group moiety in its main chain. As a consequence, its properties are completely different from those of the hydrophilic silicones heretofore in general use, such as polyether-modified silicones, and a corresponding art has thus been required for its stable incorporation into such fragile and nuanced formulations as cosmetic products and its field of use has therefore been limited. In addition, while this compound has a good compatibility with oils that are solely a silicone system, with mixed oil systems with an organic oil, phase separation has been prone to occur and this compound has thus been unable to manifest satisfactory effects.
The essential cause of these problems is intimately related to problems with the technology for producing the existing polyhydric alcohol-modified silicones. Thus, there is little freedom in the structural design of silicones modified by a polyhydric alcohol such as (poly)glycerol and production in stable qualities has been problematic. These polyhydric alcohol-modified silicones are typically produced by the addition to an organohydrogensiloxane of a polyhydric alcohol derivative that bears a reactive unsaturated group, but the residual polyhydric alcohol derivative is frequently poorly compatible with the copolymer reaction product. Separation into two phases then occurs a short time after production, which has been a major impediment to commercialization.
Moreover, due to the inherently poor compatibility between these polyhydric alcohol derivatives and organohydrogensiloxanes, the addition reaction frequently does not go to completion, even when a solvent is used, when the design molecular weight of the copolymer exceeds approximately 5000, thus making production of the target material highly problematic. Even at about 3000, unreacted material gradually separates•precipitates, which has required a process for its removal and has also been a major impediment from the standpoint of the production efficiency (Patent Documents 16 to 18).
Even when a hydroxyl-protected compound is employed as the polyhydric alcohol derivative, this necessitates deprotection after the completion of the reaction and as a consequence cannot avoid the previously noted problem of separation into two phases. In addition, severe conditions are required for the acid treatment for deprotection in this method, which causes cleavage of the silicone main chain; the desired product cannot then be obtained in good reproducibilities due to, e.g., the reduction in molecular weight (Patent Document 19).
A method of producing a branched polyglycerol-modified silicone is proposed in Patent Document 20, wherein the branched polyglycerol-modified silicone is obtained by the addition/graft polymerization of 2,3-epoxy-1-propanol in the presence of an acid or base catalyst to/on a silicone that has at least one functional group selected from the group consisting of the hydroxy group, carboxy group, amino group, imino group, mercapto group, and epoxy group. However, the siloxane main chain undergoes cleavage during graft polymerization in this method, which promotes the production of two or more components having different properties as the copolymer; this has frequently caused problems with regard to quality and the purification process.
For these reasons, the conventional polyhydric alcohol-modified silicones include few practical species, and, given the constraints on the production technology, most applied investigations have involved low molecular weight polyhydric alcohol-modified silicones. Excluding Patent Document 15, which is a block copolymer, no examples can be found of investigations of the application to cosmetic materials of high molecular weight polyglycerol-modified silicones with molecular weights above 15000. In particular, there have been no reports of the application to cosmetic materials of a high molecular weight silicone in which the side chain and/or terminal position—as opposed to the polysiloxane main chain—has been modified by a polyglycerol derivative.
On the other hand, white pigments as typified by titanium oxide and zinc oxide, colored pigments as typified by iron oxide red, and particulates such as mica and sericite are widely used in, for example, the field of cosmetic materials and most prominently basic cosmetics but also lipsticks, sunscreens, nail colors, nail coatings, foundations, mascaras, eye liners, and so forth. These powders are incorporated in cosmetic materials for the purpose, for example, of adjusting the color and covering power and/or adjusting the tactile feel, and examples of their use in oil-based cosmetic materials in combination with a conventional polyhydric alcohol-modified silicone have also been reported (Patent Documents 1 to 6 and 12 to 14).
However, particulate aggregation and sedimentation readily occurs with this art, and it has not been possible to provide the user with a fully satisfactory experience upon application to the skin due, for example, to uneven coating, an inadequate covering power, an unnatural color, and so forth. Moreover, since the polyhydric alcohol-modified silicones in use have a low molecular weight and exercise a poor oil thickening capacity, the effect with regard to cosmetic durability has also been unsatisfactory.
Among powders, silicone-type powders such as spherical organopolysiloxane elastomer powder, polymethylsilsesquioxane powder, silicone resin powder, and silicone rubber powder and organic resin powders such as silk powder, nylon powder, polymethyl methacrylate powder, and polyethylene powder exhibit an excellent oil-absorptive capacity for oils and as a consequence mitigate the strongly oily feel of oil-based cosmetics and have the effect of bringing the skin sensation after application closer to a natural impression. However, they are also difficult to uniformly disperse in a formulation, and another problem has been a conspicuous powdery sensation at increased levels of incorporation.
Accordingly, a requirement has existed for a material and/or a cosmetic material that makes possible the uniform and stable dispersion•immobilization of a powder or colorant in an oil-based cosmetic material and that makes possible the retention of an excellent cosmetic effect and a discomfort-free natural skin sensation for about 1 day after application to the skin.
Finally, the existing art related to silicone-containing gel-form cosmetic materials will be considered. Gel-form cosmetic materials evoke interest with regard to special features and effects that are based on their physical structure, and various investigations into gel-form cosmetic materials have been carried out to date. While also involving the oil thickening or gelation technology, cosmetic materials that assume a completely solidified state or that take the form of a low-viscosity liquid are frequently problematic with regard to ease of use, which may cause some limitations on their application. As a consequence, within the sphere of gel-form cosmetic materials, there have been requirements for cosmetic materials that have a viscosity and elasticity in the intermediate region between liquid and solid and for materials and technical developments that make possible the adjustment of cosmetic materials into such a state.
Accordingly, within the extensive oil thickening/gelation art, the art related to the gelatinous silicone composition of Patent Document 7, because it can bring about gelation or thickening over a broad range of silicone oils, which are oils that are quite frequently incorporated in cosmetic materials, and because of a superior composition stability over that provided by the use of a powder-based gellant, is widely utilized as a base for gel-form cosmetic materials or as a base for emulsified compositions and emulsified cosmetic materials (Patent Documents 21 to 26).
However, the polyether-modified silicone used by Patent Document 7 as a thickener•gellant requires water for gelation and the potential formulations are therefore limited. In addition, stickiness and a slimy and uncomfortable sensation are concerns depending on the particular quantity of incorporation. Another problem has been the poor thickening•gelling effect when an organic oil is present in the oil system.
Various oils other than silicone oils are used for cosmetic materials, e.g., hydrocarbon oils and ester oils, and combinations with these oils are frequently used in cosmetic material formulations in order, e.g., with regard to tactile feel, to exploit the respective advantages and compensate for respective shortcomings. Accordingly, there is demand for a gel-form cosmetic material that can maintain various oil systems comprising a silicone oil+organic oil combination in a gel state that has a viscoelasticity in the intermediate range between that of a liquid and solid. There is also demand for a gel-form cosmetic material that enables free-ranging control of the state and viscosity of the gel-form cosmetic material to be exercised based on the amount of thickener or gellant addition.    [Patent Document 1] JP 3,389,271 B (JP 06-157236 A)    [Patent Document 2] JP 3,513,682 B (JP 09-071504 A)    [Patent Document 3] JP 3,625,471 B (WO 2003/075864)    [Patent Document 4] JP 06-305933 A (JP 3,477,222 B)    [Patent Document 5] JP 07-025728 A (JP 3,160,427 B)    [Patent Document 6] JP 07-033622 A (JP 3,200,247 B)    [Patent Document 7] JP 3,333,782 B (JP 05-311076 A)    [Patent Document 8] JP 2004-182680 A    [Patent Document 9] U.S. Pat. No. 5,874,069    [Patent Document 10] U.S. Pat. No. 5,919,441    [Patent Document 11] U.S. Pat. No. 6,534,072    [Patent Document 12] JP 3,678,420 B (WO 2003/041664)    [Patent Document 13] JP 2004-231608 A    [Patent Document 14] JP 2005-194523 A    [Patent Document 15] JP 2005-042097 A    [Patent Document 16] JP 62-034039 B    [Patent Document 17] JP 3,976,226 B (JP 2002-179798 A)    [Patent Document 18] JP 2005-089494 A    [Patent Document 19] JP 06-089147 B (JP 1,956,013 B)    [Patent Document 20] JP 2004-339244 A    [Patent Document 21] JP 3,639,315 B (JP 07-100358 A)    [Patent Document 22] JP 3,407,770 B (JP 08-217626 A)    [Patent Document 23] JP 3,719,540 B (JP 09-194323 A)    [Patent Document 24] JP 3,580,384 B (JP 08-268831 A)    [Patent Document 25] JP 3,580,385 B (JP 08-268832 A)    [Patent Document 26] JP 3,313,043 B (JP 10-245317 A)